Arrangement in sieves for cellulose digesters and the like



T. SAMSON 1 LLULOSE DIGESTERS AND THE LIKE ARRANGEMENT IN SIEVES FOR CE Filed May 11, 1952 Patented Nov. 29, 1932 roas'rnrr 'saias'enorsroenrtomvr, swnnmv, ASSIGNOR r0 AKTIEBOLAGET' nonnrsna Anr-aA'ruarABaIKnanA, on s'rocxnotm; SWEDEN, A COMPANY or .sWE'DnN ARRAIIGEMENT IN srnvns non CELLULOSE nrensrnns- AND THE LIKE Application filed ma 11, 1932, Serial No. 610,727, and in Sweden November 10, 1930.

hen drawing olf digesting liquor from cellulose digesters sieves mustbe used which are placed Within the cellulose digester. If the quantities of liquor to be drawn oft" per unit of time, are considerable, the surface of the sieves should also be large. This is, particularly, the case in the circulation of digesting liquor by means of mechanical circulat ing devices. In this case, it should, however, at the same time be observed that the space of the digester should be unrestricted, as far as possible, so as not to impede the motion of the mass in the digester. For this purpose it has already been proposed to use tubes placed horizontally and arranged at some distance from the circumference of the d1- gester and extending along the whole or a part of the same. In this case, the sieve tubes have, however, been curved clrcularly and suspended in wires or stays. Such a suspen sion certainly permits the circular part the necessary dilatation and contraction. The sieve is, however, exposed to rather strong horizontal as well as vertical stresses. Besides, the wire supports have a restraining influence upon the motion of the mass through the digester.

The present invention relates to the realization of a cheaper design of the sieve tube and, at the same time, of a considerably more stable support of the said sieve tube. The invention is characterized by the fact that the sieve consists of a plurality of straight tube parts, placed at angles to each other, one or more of said tube parts being supported by brackets extending from the wall of the digester in such a way as to allow the tube or tube parts, at the point of support in the bracket or brackets, to be displaced in relation to the wall of the digester.

The tube parts may be supported to be displaced or to slide in the brackets or the brackets may have a pivot connection with the Wall of the digester. Further, the tube parts may be arranged to be displaced or to turn in relation to each other. According to a particular embodiment of the invention the tube parts are given a lancet-shape in crosssection. By this fact a large sieving surface is obtained for the large quantities of circulating liquid, required nowadays, withoutany detrimental restriction, by the sieve, upon the space ofthe digester and, particularly,

laterally. By giving the sieve such a lancetshaped, oval or oblong design, thesplinters or the mass will not be prevented from sinking downin the digester. Besides,the danger of a clogging of the splinters or the mass at the top side of the sieve will be reduced... In order to obtain a sieving surface, as

large as possible, the walls of the sieve tube are perforated, preferably in the direction towards the wall of the digester', as well as towards the center of the digester;

Other features characteristic of the invention will be more closely set forth in-the-following in connection with the embodiments,"

shown in the annexed drawings. V

Referring to the drawing,'.Fig. 1 shows a cross-section of adigester providedwith' a sieve carried out according to the invention. Fig. 2 is a crosssection of the sieve, on a larger scale, andFig. 3 is a longitudinal section. Figsd and 5'show, in cross-section and longitudinal' section, another embodiment of the suspension arrangement for the sieve, and

. Figs. 6 and 7, finally, show, diagrammatically,

two more embodiments of the suspension arrangem'ent for the sieve member. r

= In Figs. ,1 3,"1.1S;u1e wall of the digester q and '2 is the sieve member, as shown, composed of a number of straight tube parts joined at an angle to each other. The walls 3 and 4: of the sieve are curved to form arcs so as to produce an oval 0r lancet-shaped cross-section. The curved sieve-surface is provided with a number of reinforcements 5 tangentially placed, for instance consisting ofangle-irons.

The tube parts of the sieve, having an oval cross-section, are held togetherby flanges 6. The flanges are provided with pivots 7 .supported in the outer ends of the brackets 8. The brackets 8 are pivotably mounted on the brackets 9 boltedto the wall of the digester. The lower pivots 7 may preferably be carried outso as not to permit any displacement in vertical direction. i should, however, allow such a displacement.

'In the embodiment according to Figs; 4 and 5 the sieve issupportedl by brackets in The upper pivots 7- Nita sraTE-S PATENT OFFICE? the shape of hinge-irons 16 fixed to bows 17, bolted to the wall of the digester. The irons 16 embrace the sieve member with play so as to allow the sieve member to be displaced at deformations caused by variations of the temperature.

In the embodiment according to Fig. 6, thesieve member 2 is suggested to be fixed between its ends tothe wall 1 of the digester in the point 20, the ends of the member 2 be: ing mounted to slide in sliding bearings 21 (only oneis shown), arranged in brackets 22 fixed to the wall 1 of the digester. To pre:

vent breakages, the axial direction of the bearing 21 should be chosen so as to maintain, as far as possible, the angle a unchanged at occurring variations of temperature and de formations caused thereby in the sieve memher as well as in the wall of the digester. The case is somewhat complicated when the two ends of the sieve member are at some distance from the wall of the digester, as indicated by Fig. 7. In this case, the sieve member is, be.- tween its ends, attached to a bracket 25, the ends being mounted to turn in levers 26 (only one is shown) which, in their order, are

that the tube parts are given a lancet-shape in cross-section.

In testimony whereof I afiix my signature.

TORSTEN SAMSON.

mounted to turn in brackets 27 fixed to the wall of the digester. By suitably adapting not only the length of the lever 26 but also the angle that the said lever 26 forms with the radius going through the point of rotation of the lever in the bracket 27, a suspension quite free from breakage of the sieve member will be obtained for thebenefit of the durability of the plant. If the sieve member is to be constructed from a plurality of parts, turnable or slidable in relation to each other, this may, for instance, be effected by sliding the parts into each other, at a certain play.

Having now particularly described the nature of my invention and the manner of its operation, what I claim is:

1. Sieves arranged in cellulose digesters and connected with outlet pipes for digesting liquor and consisting of horizontally placed tubes located at some distance from and extending along the whole or a part of the circumference of the digester, characterized by the fact that the sieve consists of a plurality of straight tube parts, arranged at an angle with each other, one or more of said tube parts being supported in brackets extending from the wall of the digester in such a way as to allow the tube part or tube parts to be displaced in relation to the wall of the digester at variations of temperature in the digester.

2. Embodiment of the arrangement according to claim 1 characterized by the, fact that one or more of the tube parts are mounted to slide in the brackets.

3. Embodiment of the arrangement according to claim 1 characterized by the fact that one or more of the tubeparts are mounted to turn on the brackets.

1. Embodiment of the arrangement ac- 

